It never dropped combat (in PvE) which is why it's useless in instances. You either need to be far away and the last one alive in a dungeon or things will come right up to you after killing everything else and strike you down.

In the world or pvp it only drops combat on account of mobs reset in the world as soon as they can't target you and the same effect removes u from combat in pvp, loss of target.

It does work in instances. You just have to time it right. Use a threat reduction ability such as fade or something just to make sure you are the last one to be attacked, then wait for everybody else to die then Shadowmeld. This will reset the boss / encounter.

It never dropped combat (in PvE) which is why it's useless in instances. You either need to be far away and the last one alive in a dungeon or things will come right up to you after killing everything else and strike you down.

In the world or pvp it only drops combat on account of mobs reset in the world as soon as they can't target you and the same effect removes u from combat in pvp, loss of target.

You realize the two examples you've given contradicted your first statement right?

Yes, shadowmeld has been dropping your out of combat since wrath (except for a brief period in cata? that I can't think of), but its uses have been limited.

If you're the last player on their threat table, and they're not close enough to see through it, you'll drop combat.
If you're PVPing, you'll always drop combat.

I've also had instances where after a prolonged shadowmeld (20+ secs) without LoS and long range and probably something else, you'll be removed from the threat table, and the boss won't touch you.

You realize the two examples you've given contradicted your first statement right?

no they didn't. Dropping you out of combat means regardless of the circumstance you are removed from combat. Example, when a rogue vanishes they are *out of combat* even when the rest of their party is busy fighting away, regardless of their position on the threat table. Meaning if for whatever reason they crest the tank on threat, and vanish, they are removed from the table entirely. Perhaps I should said "drops you out of combat" instead of drops you out of combat.

Yes, shadowmeld has been dropping your out of combat since wrath (except for a brief period in cata? that I can't think of), but its uses have been limited.

It doesn't drop you out of combat. It used to long ago, allowing you to eat, drink and even bandage while shadowmelded, but somehow this was deemed OP and promptly changed. So long as you are on a threat table and can't eat you're in combat.

If you're the last player on their threat table, and they're not close enough to see through it, you'll drop combat.
If you're PVPing, you'll always drop combat.

Which means basically, if you're not a healer or not doing the absolute worst, most abyssmal dps, you really can't count on it to save you.

I've also had instances where after a prolonged shadowmeld (20+ secs) without LoS and long range and probably something else, you'll be removed from the threat table, and the boss won't touch you.

Never had that happen in my experience. What happens is after the boss runs around killing everyone, it runs up to you as if you're not melded at all, and clobbers you; the exceptions being if I've feigned death, gone invisible or vanished prior to shadowmelding (and had a random AoE break those abilities) as those abilities do remove you from the threat table entirely.

AFAIK it works like Feign Death in that it doesn't drop combat, it just sets your threat to zero. The behaviour for all(?) PvE mobs (except bosses) is to drop combat when their threat tables only have zeroes in them... so the other people on their tables need to be dead or vanished as well. Having said that, Shadowmeld is a bit flaky, and always has been. On top of that, in the Dread Wastes on certain dailies the combat flag is very sticky.

FWIW, I've been pulling Shadowmeld + Flightform bullshit on my gatherdruid since at least WotLK... so it definitely can drop combat. YMMV YHBW.